Preoperative fibrinogen plasma concentration is associated with perioperative bleeding and transfusion requirements in scoliosis surgery

Effect of Prophylactic Fibrinogen Concentrate In Scoliosis Surgery (EFISS): a study protocol of two-arm, randomised trial

INTRODUCTION

Fibrinogen is one of the essential coagulation factors. Preoperative lower plasma fibrinogen level has been associated with higher blood loss. Scoliosis surgery presents a challenge for the anaesthetic team, one of the reasons being blood loss and transfusion management. Recently, the prophylactic fibrinogen administration has been a debated topic in various indications. It has been described for example, in urological or cardiovascular surgery, as well as in paediatrics. This pilot study is focused on verifying the feasibility of potential large randomised trial and verifying the safety of prophylactic fibrinogen administration in paediatric scoliosis surgery.

METHODS AND ANALYSIS

A total of 32 paediatric patients indicated for scoliosis surgery will be recruited. Participants will be randomised into study groups in a 1:1 allocation ratio. Patients in the intervention group will receive prophylactic single dose of fibrinogen, in addition to standard of care. Patients in the control group will receive standard of care without study medication prior to skin incision. The primary aim is to assess the safety of prophylactic fibrinogen administration during scoliosis surgery in children, the incidence of any adverse events (AEs) and reactions will be monitored during participation in the study. The secondary objective is to investigate the additional safety information, feasibility and efficacy of a prophylactic fibrinogen administration. The incidence of AEs and reactions according to selected adverse events of special interest will be monitored. All collected data will be subjected to statistical analysis according to a separate statistical analysis plan.

ETHICS AND DISSEMINATION

This trial follows the applicable legislation and requirements for good clinical practice according to the International Conference on Harmonisation E6(R2). All essential trial documents were approved by the relevant ethics committee and national regulatory authority (State Institute for Drug Control) and their potential amendments will be submitted for approval.

TRIAL REGISTRATION NUMBER

NCT05391412.

Plasma Fibrinogen as a Predictor of Perioperative-Blood-Component Transfusion in Major-Nontraumatic-Orthopedic-Surgery Patients: A Cohort Study

There is a trend towards increased perioperative bleeding in patients with plasma fibrinogen levels < 200 mg/dL^-1. This study aimed to assess whether there is an association between preoperative fibrinogen levels and perioperative blood-product transfusion up to 48 h after major orthopedic surgery. This cohort study included 195 patients who underwent primary or revision hip arthroplasty for nontraumatic etiologies. Plasma fibrinogen, blood count, coagulation tests, and platelet count were measured preoperatively. A plasma fibrinogen level of 200 mg/dL^-1 was the cutoff value used to predict blood transfusion. The mean (SD) plasma fibrinogen level was 325 (83) mg/dL^-1. Only thirteen patients had levels < 200 mg/dL^-1, and only one of them received a blood transfusion, with an absolute risk of 7.69% (1/13; 95%CI: 1.37-33.31%). Preoperative plasma fibrinogen levels were not associated with the need for blood transfusion (p = 0.745). The sensitivity and the positive predictive value of plasma fibrinogen < 200 mg/dL^-1 as a predictor of blood transfusion were 4.17% (95%CI: 0.11-21.12%) and 7.69% (95%CI: 1.12-37.99%), respectively. Test accuracy was 82.05% (95%CI: 75.93-87.17%), but positive and negative likelihood ratios were poor. Therefore, preoperative plasma fibrinogen level in hip-arthroplasty patients was not associated with the need for blood-product transfusion.

Predictors of perioperative blood loss in primary posterior hemivertebra resection for pediatric patients with congenital scoliosis

Several studies have elucidated the risk factors of intraoperative bleeding. However, the total blood loss (visible and hidden loss) and related risk factors were seldom reported. In this study, we aimed to identify predictors of massive blood loss in posterior hemivertebra resection for pediatric patients. Clinical records were retrospectively reviewed for 108 pediatric patients who underwent primary posterior hemivertebra resection and spinal fusion for congenital scoliosis from June 2017 to June 2019. Intraoperative blood loss was recorded and hidden blood loss was calculated by deducting the intraoperative loss from the total blood loss calculated using specific formula. Perioperative information was collected for multivariable linear regression analysis to determine the independent risk factors of the blood loss. The mean total blood loss was 575.0 ± 318.0 ml during the perioperative period, accounting for 42.1% of the estimated blood volume. The intraoperative and hidden loss were 337.6 ± 179.5 ml and 237.4 ± 204.8 ml, respectively, accounting for 58.7 and 41.3% of the total loss. Multivariable linear regression indicated that age, preoperative Cobb angle, operative time, and number of fused levels were independent risk factors of the total blood loss. Patients with operative time ≥145 minutes, fused levels ≥4, and preoperative Cobb angle ≥40° have an increased risk of massive blood loss. The perioperative blood loss of surgery for congenital scoliosis was considerable, with a high percentage of hidden blood loss. Patients with severe deformity, more fused levels, and longer operative time had higher risk of massive blood loss.

Does Abnormal Preoperative Coagulation Status Lead to More Perioperative Blood Loss in Spinal Deformity Correction Surgery?

This study aims to analyze the potential association between the preoperative coagulation status and perioperative blood loss in spinal deformity correction surgery. The preoperative coagulation status and estimated blood loss (EBL) during operation, postoperative wound drainage, and allogeneic transfusion during and after operation were recorded and analyzed. Among the 164 patients, 26 had a longer prothrombin time (PT), 13 had a lower fibrinogen level, 55 had a longer activated partial thromboplastin time (APTT), and 2 had a longer thrombin time (TT), and the platelet count (PLT) was all normal or higher than the normal level. The mean EBL per surgical level was 77.8 ml (range, 22–267 ml), and the mean drainage per surgical level was 52.7 ml (range, 7–168 ml). Fifty-five patients and 12 patients underwent allogeneic transfusion during and after the operation, respectively. The differences in EBL per surgical level, mean drainage per surgical level, the occurrences of allogeneic transfusion during and after operation between the patients with a longer PT, lower fibrinogen level, longer APTT or longer TT, and the normal controls were not significant (all P’s > 0.05). The Spearman correlation analysis showed that there was no correlation between PT, fibrinogen, APTT, TT or PLT with EBL per surgical level, mean drainage per surgical level, or allogeneic transfusion during and after the operation (all P’s > 0.05). The abnormal preoperative coagulation status but not hemophilia does not lead to more perioperative blood loss or a higher rate of perioperative allogeneic transfusion in spinal deformity correction surgery.

Thrombotic activation before and after total hip arthroplasty. A prospective cohort study

BACKGROUND

Total hip arthroplasty (THA) causes acute blood loss. It may lead to a deficiency in coagulation factors, which, in turn, may lead to increased bleeding during the postoperative period.

METHODS

Thirty patients (18 women) with a mean age of 67 years (range: 63-72 years) participated in this prospective diagnostic study. THA was performed without tranexamic acid administration in the perioperative period. Activities of clotting factors II, VIII, X, and fibrinogen concentration were evaluated before surgery, 6 hours after the procedure, 2, 4, and 6 days after the operation. All laboratory tests were performed using ACL TOP 500 CTS analyzer.

RESULTS

No thromboembolic complications were noted during hospitalization. Mean fibrinogen concentration was 366 mg/dL before surgery, which decreased to 311 mg/dL 6 hours after the operation and peaked at 827 mg/dL on the 4th day after the procedure. Activities of factors II and X decreased on the second and fourth days after surgery. Although the activity of factor VIII decreased after the procedure, it remained within the normal range. Increased baseline fibrinogen concentrations were observed in 6 out of 30 (20%) patients. Mean blood loss was 1332 mL (range, 183-2479 mL) and did not correlate with changes in clotting factor activities.

CONCLUSIONS

In patients undergoing THA, fibrinogen acts as an acute-phase protein. Activities of clotting factors II and X normalize within 6 days, and although the activity of factor VIII decreases, it remains within the normal range.

TRIAL REGISTRATION

The study was pre-registered May 1st, 2020 on ClinicalTrials.gov.

Impact of Preoperative Platelet Count on Bleeding Risk and Allogeneic Transfusion in Multilevel Spine Surgery

STUDY DESIGN

This was an observational cohort study of patients receiving multilevel thoracic and lumbar spine surgery.

OBJECTIVE

The aim of this study was to identify which patients are at high risk for allogeneic transfusion which may allow for better preoperative planning and employment of specific blood management strategies.

SUMMARY OF BACKGROUND DATA

Multilevel posterior spine surgery is associated with a significant risk for major blood loss, and allogeneic blood transfusion is common in spine surgery.

METHODS

A univariate logistic regression model was used to identify variables that were significantly associated with intraoperative allogeneic transfusion. A multivariate forward stepwise logistic regression model was then used to measure the adjusted association of these variables with intraoperative transfusion.

RESULTS

Multilevel thoracic and lumbar spine surgery was performed in 921 patients. When stratifying patients by preoperative platelet count, patients with pre-operative thrombocytopenia and severe thrombocytopenia had a significantly higher rate of transfusion than those who were not thrombocytopenic. Furthermore, those with severe thrombocytopenia had a higher rate of red blood cells, fresh frozen plasma, and platelet transfusion than those with higher platelet counts. Multivariate logistic regression found that preoperative platelet count was the most significant contributor to transfusion, with a platelet count ≤100 having an adjusted odds ratio (OR) of transfusion of 4.88 (95% confidence interval [CI] 1.58-15.02, P = 0.006). Similarly, a platelet count between 101and 150 also doubled the risk of transfusion with an adjusted OR of 2.02 (95% CI 1.01-4.04, P = 0.047). The American Society of Anesthesiologists classification score increased the OR of transfusion by 2.5 times (OR = 2.52, 95% CI 1.54-4.13), whereas preoperative prothrombin time and age minimally increased the risk.

CONCLUSION

Preoperative thrombocytopenia significantly contributes to intraoperative transfusion in multilevel thoracic lumbar spine surgery. Identifying factors that may increase the risk for transfusion could be of great benefit in better preoperative counseling of patients and in reducing overall cost and postoperative complications by implementing strategies and techniques to reduce blood loss and blood transfusions.

LEVEL OF EVIDENCE

2.

A randomised controlled trial of fibrinogen concentrate during scoliosis surgery

Bleeding and blood transfusion are common after scoliosis surgery. Fibrinogen is essential for blood clot formation and depletes quickly during haemorrhage. We randomly allocated 102 children 12-18 years old having surgery for idiopathic scoliosis, 51 to intra-operative fibrinogen concentrate 30 mg.kg^-1 (maximum 2 g) and 51 to saline placebo. Fibrinogen reduced peri-operative blood loss by a median (95%CI) volume of 155 (5-320) ml, from a median (IQR [range]) of 1035 (818-1420 [400-3030]) ml to 885 (755-1155 [270-2645]) ml, p = 0.04. Seven and four children received allogeneic red blood cell transfusion after fibrinogen and placebo, respectively, p = 0.34. There were no side-effects.

A comparative study of fibrinogen measurement using TEG® functional fibrinogen and Clauss in adolescents undergoing scoliosis surgery

INTRODUCTION

Thromboelastography (TEG®) functional fibrinogen (FF) test is a point-of-care test for fibrinogen measurement and is preferred for its rapid turnaround time. This study was designed to compare TEG® functional fibrinogen level (FLEV) with classic Clauss fibrinogen in patients undergoing scoliosis surgery and to evaluate the concordance between the two methods.

METHODS

Patients in this study were part of a larger study evaluating the effect of fibrinogen concentrate (FC) supplementation on perioperative blood loss in scoliosis surgery. Paired samples for TEG® FF and Clauss fibrinogen assays were taken from 40 patients at three different timepoints perioperatively. The agreement between FLEV and Clauss was assessed, and the possibility of using FLEV measurements to predict Clauss fibrinogen was explored.

RESULTS

One hundred and seventeen paired samples from 39 patients were finally analyzed. Pearson correlation test confirmed positive linear correlations between FLEV and Clauss at all three timepoints (r = .70, .67, and .66 at baseline, before FC administration, and after FC administration, respectively; P < .001 for all) and together for all measures (r = .76, P < .001), while Bland-Altman plots showed FLEV significantly overestimated Clauss constantly. Optimum diagnostic values of FLEV at 4.27 and 3.77 g/L were generated to predict normal fibrinogen as Clauss ≥ 3.0 g/L (AUROC 0.941, 95% CI: 0.891-0.991) and critical intraoperative hypofibrinogenemia as Clauss ≤ 2.0g/L (AUROC 0.894, 95% CI: 0.838-0.950), respectively.

CONCLUSIONS

In adolescents undergoing scoliosis surgery, FLEV correlated linearly with Clauss fibrinogen. Though FLEV overestimates Clauss constantly, FLEV values are able to predict hypofibrinogenemia and normal fibrinogen with both AUROC > 0.85.

Relationship Between Preoperative Plasma Fibrinogen Concentration, Perioperative Bleeding, and Transfusions in Elective Adult Spinal Deformity Correction

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

This study sought to investigate the relationship between preoperative (preop) fibrinogen, bleeding, and transfusion requirements in adult spinal deformity corrections.

SUMMARY OF BACKGROUND DATA

Blood loss after major spinal reconstruction increases the risks and costs of surgery. Preoperative fibrinogen levels may predict intra- and postoperative blood loss.

METHODS

Data were collected from clinic charts and hospital medical records of all 142 of a single surgeon's consecutive adult spine patients undergoing 7 or more levels deformity correction surgeries from January 2011 to December 2014. t tests were used to compare perioperative variables between patients with total blood loss in the upper quartile (≥1,000 mL) and the remaining patients. Similarly, patients receiving >2 units of packed red cells (PRCs) were compared with others. Analysis of variance was used to compare the blood loss between the patients' groups (quartiles) based on their preoperative fibrinogen concentration.

RESULTS

Mean total blood loss was 847.9 (±543.6) mL. Overall, mean preoperative fibrinogen concentration was 254.8 (±82.9) mg/dL. Patients with lower fibrinogen concentration (<193 mg/dL) experienced significantly higher blood loss than those with higher concentrations (p < .05). Patients with transfusion >2 units PRC had significantly greater number of spinal levels treated, higher mean operative time, total blood loss and lower mean preoperative fibrinogen than those transfused 2 or fewer units PRC (p < .05). Total blood loss correlated significantly with preoperative fibrinogen concentration (r = -0.51, p < .05). All the thromboelastography (TEG) variables (G, K, and Angle) correlated significantly with preoperative fibrinogen (p < .05).

CONCLUSIONS

In our cohort undergoing correction of adult spinal deformity, patients with preoperative fibrinogen level lower than 193 mg/dL had significantly higher bleeding than their counterparts. Perioperative transfusion requirements correlated moderately both with the blood loss and preoperative fibrinogen concentration. Incorporation of preoperative fibrinogen allows better prediction of total perioperative blood loss and may therefore guide the treatment team in use of ameliorating therapies.

LEVEL OF EVIDENCE

Level IV.

Effects of storage over a 36-month period on coagulation factors in a canine plasma product obtained by use of plasmapheresis

OBJECTIVE

To evaluate stability of coagulation factors in canine plasma obtained by use of plasmapheresis and stored over a 36-month period.

SAMPLE

Canine plasma obtained by use of plasmapheresis acquired from a commercial blood bank.

PROCEDURES

Coagulation testing for fibrinogen concentration and activity of factors II, V, VII, VIII, and IX and von Willebrand factor was performed on canine plasma obtained by use of plasmapheresis. Samples were obtained for testing at 6-month intervals from plasma stored for up to 36 months.

RESULTS

A simple mixed linear regression model was created for each analysis. Median value for the fibrinogen concentration was > 150 mg/dL for all time points, except at 467, 650, and 1,015 days of storage. Median value for factor VIII was > 70% only at 650 days. Median value for factor V was > 50% through 650 days. Median value for factors VII and X was > 50% through 833 days, and median value for factors II and VII was > 50% through 1,015 days. Median value for von Willebrand factor was > 50% for the entire study (1,198 days). Median value for factor X was always < 50%.

CONCLUSIONS AND CLINICAL RELEVANCE

Coagulation factors degraded over time at variable rates, and all labile factors remained at > 50% activity for longer than 1 year. Plasma collected by plasmapheresis potentially offers prolonged life span of some clotting factors. Plasmapheresis is an acceptable form of canine plasma collection for transfusion purposes, and further studies should be performed to determine all of its benefits.

Predictors for blood loss in pediatric patients younger than 10 years old undergoing primary posterior hemivertebra resection: a retrospective study

Background

Blood loss during hemivertebra resection may be substantial. Few studies have examined the risk factors of blood loss undergoing hemivertebra resection, especially those in patients under 10 years old.

Methods

Patients under 10 years old diagnosed with congenital scoliosis and hemivertebra were retrospectively included from January 2014 to October 2017. They all had primary posterior hemivertebra resection at Peking Union Medical College Hospital. Perioperative information was collected and multivariable linear logistic regression was performed to determine the independent risk factors of blood loss.

Results

One hundred three patients were included. The mean total blood loss was 346 + 178 ml. The percentage of total blood loss to the EBV was 27.0 + 13.3%. Multivariable linear logistic regression indicated that preoperative total Cobb angle (P = 0.046) and the number of fused levels (P < 0.001) were independent risk factors of total blood loss. Preoperative platelet count and preoperative coagulation function were not associated with blood loss in patients undergoing hemivertebra resection.

Conclusions

Preoperative total Cobb angle and the number of fused levels determined the blood loss for patients undergoing hemivertebra resection.

Preoperative Immune Response is Associated with Perioperative Transfusion Requirements in Glioma Surgery

Immunosuppression induced by transfusion causes postoperative adverse events including poor prognosis in cancer, but data on influence of the immune response on blood transfusion requirements during perioperative period are limited. The aim of this study was to investigate whether the preoperative immune response is associated with perioperative blood cell transfusion in a glioma surgical patient population. The authors identified 321 cases of surgery for treatment of glioma. Patient variables, preoperative laboratory variables (hemoglobin, platelet count, activated partial thromboplastin time, prothrombin time, hematocrit, red and white blood cell count), and transfusions were registered. Plasma concentration of Th-associated cytokines was measured by flow cytometry. Multivariable regression analysis and receiver operating characteristic curve were undertaken to identify predictors of transfusion. Of 321 patients, 157 (48.90%) received red blood cells transfusion. The mean age is significantly higher in transfusion group compared to no transfusion group, while postoperative hospital stay, preoperative hemoglobin, prothrombin time, activated partial thromboplastin time, platelet count, red and white blood cell count and hematocrit of patients did not differ significantly between the two groups. No significant differences of IL-2, -4, -6, -10 and INF-γ concentration were observed between transfusion and no transfusion group. The concentration of TNF and IL-17A was significantly lower in transfusion patients than in the no transfusion subjects. Low plasma TNF and IL-17A levels predicted high perioperative transfusion rate, the combination of them enlarged the prognostic accuracy of testing. Our study demonstrates that the preoperative immune response influences transfusion requirements, and TNF and IL-17 are important predictive risk factors for perioperative use of blood components in glioma patients.

The Effect of Fibrinogen on Blood Loss After Lumbar Surgery: A Double-Blind Randomized Clinical Trial

Background

Spinal surgeries often have a high risk of hemorrhage during and after surgery, thus most patients require blood transfusions and blood products. Fibrinogen is used in different forms to control hemorrhage.

Objectives

The present study aimed to evaluate the outcomes of prophylactic fibrinogen administration in reducing hemorrhage after lumbar surgery.

Methods

This was a randomized clinical trial conducted on 30 patients undergoing lumbar surgery. The levels of fibrinogen, as well as hemoglobin (HB), hematocrit (HCT), prothrombin time (PT), partial thromboplastin time (PTT), and INR, were assessed preoperatively as the baseline values. The patients were divided into two groups: intervention (N = 15) and control (N = 15) groups. The intervention group received 1 g fibrinogen dissolved in 50 cc distilled water with surgical incision and the control group received 50 cc distilled water with the surgical incision. At the end of the operation, the volume of hemorrhage transfused blood products (fresh frozen plasma, packed cell, and platelet) was measured. In addition, at 0, 6, and 24 hours after the end of surgery and transfer to recovery, serum levels of fibrinogen, HB, HCT, INR, PT, PTT, and hemovac drain volume were measured.

Results

The hemorrhage during and after the operation in the control group was significantly higher than that of the intervention group (P < 0.05). There were no significant differences between hemoglobin and serum level of fibrinogen before and after surgery between the two groups. The postoperative hypotension showed no significant difference between the two groups.

Conclusions

The findings showed the effectiveness of fibrinogen in reducing acute hemorrhage. Considering the adverse consequences of hemorrhage and coagulopathy in patients undergoing surgery, using fibrinogen as prophylaxis is recommended in surgeries with high risks of hemorrhage.

Development of Consensus Based Best Practice Guidelines for Perioperative Management of Blood Loss in Patients Undergoing Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

STUDY DESIGN

Delphi process with multiple iterative rounds using a nominal group technique.

OBJECTIVE

The aim of this study was to use expert opinion to achieve consensus on various methods for minimizing blood loss in patients undergoing posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

BACKGROUND DATA

Perioperative blood loss management represents a critical component of safely performing PSF in children with AIS. Little consensus exists on ways to mitigate excessive blood loss after PSF.

METHODS

An expert panel composed of 21 pediatric spine surgeons was selected. Using the Delphi process and iterative rounds using a nominal group technique, participants in this panel were presented with a detailed literature review and asked to voice opinion collectively during three rounds of voting. Agreement >80% was considered consensus. Interventions without consensus were discussed and revised, if feasible.

RESULTS

Consensus was reached to support 21 best practice guideline measures for perioperative management of blood loss in patients undergoing PSF for AIS. Areas included preoperative assessment and preparation, intraoperative strategies to decrease blood loss, and postoperative transfusion indications.

CONCLUSION

We present a consensus-based best practice guideline consisting of 21 recommendations for strategies to minimize and manage blood loss during PSF. This can serve to reduce variability in practice in this area, help develop hospital specific protocols, and guide future research.

Dilutional coagulopathy in pediatric scoliosis surgery: A single center report

BACKGROUND

Children undergoing posterior spinal fusion experience high blood loss often necessitating transfusion. An appropriately activated coagulation system provides hemostasis during surgery, but pathologic dysregulation can cause progressive bleeding and increased transfusions. Despite receiving antifibrinolytics for clot stabilization, many patients still require transfusions.

AIMS

We sought to examine the association of dilutional coagulopathy with blood loss and blood transfusion in posterior spinal fusion for pediatric scoliosis patients.

METHODS

A retrospective, single institution study of children undergoing posterior spinal fusion >6 levels with a standardized, prospective anesthetic protocol utilizing antifibrinolytics. Blood loss was evaluated using a hematocrit-based calculation. To evaluate transfusions, a normalized Blood Product Transfusion calculation was developed. Factors associated with blood loss and blood transfusions were determined by univariate analysis and multivariate regression modeling with multicollinearity and mediation analysis.

RESULTS

Patients received 73.7 mL/kg (standard deviation ±30.8) of fluid poor in coagulation factors. Estimated blood loss was 42.6 mL/kg (standard deviation ±18.0). There was a significant association between estimated blood loss and total fluids delivered (Spearman's rho = 0.51, 95% confidence interval 0.33-0.65, P < 0.001). Factors significantly associated with normalized Blood Product Transfusion in this cohort included age, weight, scoliosis type, levels fused, total osteotomies, pelvic fixation, total fluid, maximum prothrombin time, and minimum fibrinogen. Regression modeling showed the best combination of variables for modeling normalized Blood Product Transfusion included patient weight, number of levels fused, total fluid administered, and maximum prothrombin time.

CONCLUSION

Blood product transfusion remains a frustrating problem in pediatric scoliosis. Identifying and controlling dilutional coagulopathy in these patients may reduce blood loss and the need for blood transfusion.

Coagulation Profile as a Risk Factor for 30-day Morbidity Following Cervical Laminectomy and Fusion

STUDY DESIGN

Retrospective analysis of prospectively collected data.

OBJECTIVE

The aim of this study was to determine the ability of abnormal coagulation profile to predict adverse events following posterior cervical laminectomy and fusion (PCLF).

SUMMARY OF BACKGROUND DATA

PCLF is an increasingly common procedure used to treat a variety of traumatic and degenerative spinal conditions. Abnormal coagulation profile is associated with postoperative adverse events, including blood transfusion. There is a paucity of literature that specifically addresses the relationship between coagulation profile and complications following PCLF.

METHODS

ACS-NSQIP was utilized to identify patients undergoing PCLF between 2006 and 2013. A total of 3546 patients met inclusion criteria. Multivariate analysis was utilized to identify associations between abnormal coagulation profile and postoperative complications.

RESULTS

Membership in the low-platelet cohort was an independent risk factor for myocardial infarction (Odds Ratio (OR) = 5.4 [1.0, 29.1], P = 0.049) and bleeding transfusion (OR = 2.0 [1.2, 3.4], P = 0.011). Membership in the high international normalized ratio group was an independent risk factor for pneumonia (OR = 6.3 [2.5, 16.1], P < 0.001), ventilation >48 hours (OR = 6.5 [2.3, 18.4], P < 0.001), organ space surgical site infection (OR = 11.1 [2.1, 57.3], P = 0.004), urinary tract infection (OR = 3.0 [1.2, 8.0], P = 0.024), bleeding transfusion (OR = 6.0 [3.4, 10.7], P < 0.001), sepsis (OR = 5.1 [1.6, 16.4], P = 0.006), and septic shock (OR = 6.8 [1.7, 27.4], P = 0.007). Membership in the bleeding disorders cohort was an independent predictor of unplanned intubation (OR = 3.2 [1.1, 9.5], P = 0.041), pneumonia (OR = 2.9 [1.2, 7.2], P = 0.023), ventilation >48 hours (OR = 4.8 [1.9, 12.4], P = 0.001), cerebrovascular accident/stroke with neurological deficit (OR = 24.8 [2.9, 210.6], P = 0.003), bleeding transfusion (OR = 2.1 [1.1, 4.1], P = 0.032), reoperation (OR = 3.6 [1.4, 9.3], P = 0.008), and sepsis (OR = 3.4 [1.1, 10.4], P = 0.031).

CONCLUSION

This is the first large study to document abnormal coagulation profile as an independent predictor of outcomes following PCLF. Abnormal coagulation profile represents a predictor of complications that can be medically mitigated, and is therefore a valuable parameter to assess preoperatively. Coagulation profile should continue to play a role in targeting patients for risk stratification, preoperative optimization, and quality improvement initiatives.

LEVEL OF EVIDENCE

3.

Tocilizumab treatment in patients with rheumatoid arthritis is associated with reduced fibrinogen levels and increased blood loss after total knee arthroplasty

OBJECTIVE

Since IL-6 has been associated with activation of the coagulation cascade and upregulation of fibrinogen transcription, we retrospectively tested the hypothesis that patients with rheumatoid arthritis (RA) treated with tocilizumab (TCZ) may lose more blood when undergoing total knee arthroplasty (TKA).

METHODS

This study included 115 RA patients who underwent primary TKA and were preoperatively tested for fibrinogen levels. The blood volume of each patient was calculated using the Nadler formula, and estimated blood loss after TKA was calculated as the change between pre-operative and post-operative hematocrits. If salvaged blood was reinfused, the volume was measured and added to the volume of the estimated blood loss.

RESULTS

We observed that patients treated with TCZ had significantly lower pre-operative fibrinogen levels than those not treated with TCZ (190.0 mg/dL versus 347.0 mg/dL, respectively; p = .00018). We also observed a statistically significant increase in mean total volume of estimated blood loss after TKA in RA patients who had been treated with TCZ compared with those not treated with TCZ (797.1 mL versus 511.4 mL, respectively; p = .0039).

CONCLUSION

TCZ treatment in patients with RA may increase the risk of blood loss after TKA because of decreased fibrinogen levels.

Is Preoperative Fibrinogen Testing Associated With Total Blood Loss in Adolescent Idiopathic Scoliosis Correction?

STUDY DESIGN

Retrospective analysis.

OBJECTIVE

This study sought to investigate the potential association between preoperative fibrinogen, bleeding, and transfusion requirements in adolescent idiopathic scoliosis (AIS) corrections.

SUMMARY OF BACKGROUND DATA

Blood loss after major spinal reconstruction increases the risks and costs of surgery. Preoperative fibrinogen levels may predict intra- and postoperative blood loss.

METHODS

Data were collected from clinic charts and hospital medical records of all 110 of a single surgeon's consecutive AIS patients undergoing greater than three-level deformity correction surgeries from January 2011 to December 2013. Pearson test was used to investigate the correlation between bleeding and clinical variables, with level of significance set at α = 0.05.

RESULTS

Mean total bleeding volume was 488 (±356) mL. Overall, mean preoperative fibrinogen concentration was 188.6 ± 32.8 mg/dL. Preoperative platelet counts, prothrombin time (PT), and activated partial thromboplastin time (aPTT) did not correlate significantly with preoperative fibrinogen concentration (p > .05). Both packed red cells (PRC) and packed red blood cells (PRBC) correlated significantly with preoperative fibrinogen (p < .05). The correlation between PRC and preoperative fibrinogen was -0.042. There was a negative correlation between PRBC and preoperative fibrinogen (r = -0.46). Overall mean thromboelastography (TEG) values were within normal range in both males and females and both had comparable TEG parameter values. All the TEG variables (G, K, and Angle) correlated significantly with preoperative fibrinogen (p < .05) but not with total blood volume (p > .05). The correlation coefficient between these TEG variables and preoperative fibrinogen were 0.51, 0.59, and 0.54, respectively. The total bleeding volume and % estimated blood volume correlated significantly with both PRC (r = 0.352, r = 0.376; p < .05) and PRBC (r = 0.621, r = 0.614; p < .05).

CONCLUSIONS

In our cohort undergoing correction of AIS, preoperative fibrinogen levels exhibited a significant negative logarithmic correlation with total blood loss. TEG variables also correlated significantly with preoperative fibrinogen levels. Efforts should be made to incorporate this measure in perioperative blood management program for AIS corrections.

LEVEL OF EVIDENCE

Level IV.

Perioperative Blood Management in Pediatric Spine Surgery

Blood management strategies are integral to successful outcomes in many types of orthopaedic surgery. These strategies minimize blood loss and transfusion requirements, ultimately decreasing complications, improving outcomes, and potentially eliminating risks associated with allogeneic transfusion. Practices to achieve these goals include preoperative evaluation and optimization of hemoglobin, the use of pharmacologic agents or anesthetic methods, intraoperative techniques to improve hemostasis and cell salvage, and the use of predonated autologous blood. Guidelines can also help manage allogeneic transfusions in the perioperative period. Although the literature on blood management has focused primarily on arthroplasty and adult spine surgery, pediatric spinal fusion for scoliosis involves a large group of patients with a specific set of risk factors for transfusion and distinct perioperative considerations. A thorough understanding of blood management techniques will improve surgical planning, limit transfusion-associated risks, maintain hemostasis, and optimize outcomes in this pediatric population.

The Effect of Ex Vivo Factor XIII Supplementation on Clot Formation in Blood Samples From Cardiac and Scoliosis Surgery Patients

Excessive perioperative bleeding remains a substantial problem. Factor XIII (FXIII) contributes to clot stability, and it has therefore been suggested that supplementation with FXIII concentrate may improve perioperative hemostasis. We evaluated the effects of increasing doses of FXIII, alone or in combination with fibrinogen or platelet concentrate, in blood samples from 2 considerably different groups of surgical patients: cardiac and scoliosis surgery patients. Whole-blood samples were collected immediately after operation from cardiac and scoliosis surgery patients. The samples were supplemented with 3 clinically relevant doses of FXIII concentrate (+20%, +40%, and +60%), alone or in combination with a fixed dose of fibrinogen concentrate (+1.0 g/L) or fresh apheresis platelets (+92 × 10⁹/L). Clot formation was assessed with rotational thromboelastometry (ROTEM). When the highest dose of FXIII concentrate was added, EXTEM clotting time was shortened by 10% in both cardiac and scoliosis surgery patients (95% confidence intervals: 2.4%-17% and 3.3%-17%, respectively), and FIBTEM maximum clot firmness was increased by 25% (9.3%-41%) in cardiac patients, relative to baseline. When fibrinogen was added, the dose-dependent effect of FXIII on clot stability was maintained, but the total effect was markedly greater than with FXIII alone, +150% (100%-200%) and +160% (130%-200%) for the highest FXIII dose in cardiac and scoliosis patients, respectively. Ex vivo supplementation with clinically relevant doses of FXIII improved clot formation moderately in blood samples from cardiac and scoliosis surgery patients, both alone and when given in combination with fibrinogen or platelet concentrate.

Crotalus atrox venom preconditioning increases plasma fibrinogen and reduces perioperative hemorrhage in a rat model of surgical brain injury

Perioperative bleeding is a potentially devastating complication in neurosurgical patients, and plasma fibrinogen concentration has been identified as a potential modifiable risk factor for perioperative bleeding. The aim of this study was to evaluate preconditioning with Crotalus atrox venom (Cv-PC) as potential preventive therapy for reducing perioperative hemorrhage in the rodent model of surgical brain injury (SBI). C. atrox venom contains snake venom metalloproteinases that cleave fibrinogen into fibrin split products without inducing clotting. Separately, fibrinogen split products induce fibrinogen production, thereby elevating plasma fibrinogen levels. Thus, the hypothesis was that preconditioning with C. atrox venom will produce fibrinogen spilt products, thereby upregulating fibrinogen levels, ultimately improving perioperative hemostasis during SBI. We observed that Cv-PC SBI animals had significantly reduced intraoperative hemorrhage and postoperative hematoma volumes compared to those of vehicle preconditioned SBI animals. Cv-PC animals were also found to have higher levels of plasma fibrinogen at the time of surgery, with unchanged prothrombin time. Cv-PC studies with fractions of C. atrox venom suggest that snake venom metalloproteinases are largely responsible for the improved hemostasis by Cv-PC. Our findings indicate that Cv-PC increases plasma fibrinogen levels and may provide a promising therapy for reducing perioperative hemorrhage in elective surgeries.

Pediatric Patient Blood Management Programs: Not Just Transfusing Little Adults

Red blood cell transfusions are a common life-saving intervention for neonates and children with anemia, but transfusion decisions, indications, and doses in neonates and children are different from those of adults. Patient blood management (PBM) programs are designed to assist clinicians with appropriately transfusing patients. Although PBM programs are well recognized and appreciated in the adult setting, they are quite far from standard of care in the pediatric patient population. Adult PBM standards cannot be uniformly applied to children, and there currently is significant variation in transfusion practices. Because transfusing unnecessarily can expose children to increased risk without benefit, it is important to design PBM programs to standardize transfusion decisions. This article assesses the key elements necessary for a successful pediatric PBM program, systematically explores various possible pediatric specific blood conservation strategies and the current available literature supporting them, and outlines the gaps in the evidence suggesting need for further/improved research. Pediatric PBM programs are critically important initiatives that not only involve a cooperative effort between pediatric surgery, anesthesia, perfusion, critical care, and transfusion medicine services but also need operational support from administration, clinical leadership, finance, and the hospital information technology personnel. These programs also expand the scope for high-quality collaborative research. A key component of pediatric PBM programs is monitoring pediatric blood utilization and assessing adherence to transfusion guidelines. Data suggest that restrictive transfusion strategies should be used for neonates and children similar to adults, but further research is needed to assess the best oxygenation requirements, hemoglobin threshold, and transfusion strategy for patients with active bleeding, hemodynamic instability, unstable cardiac disease, and cyanotic cardiac disease. Perioperative blood management strategies include minimizing blood draws, restricting transfusions, intraoperative cell salvage, acute normovolemic hemodilution, antifibrinolytic agents, and using point-of-care tests to guide transfusion decisions. However, further research is needed for the use of intravenous iron, erythropoiesis-stimulating agents, and possible use of whole blood and pathogen inactivation. There are numerous areas where newly formed collaborations could be used to investigate pediatric transfusion, and these studies would provide critical data to support vital pediatric PBM programs to optimize neonatal and pediatric care.

Human plasma protein N-glycosylation

Glycosylation is the most abundant and complex protein modification, and can have a profound structural and functional effect on the conjugate. The oligosaccharide fraction is recognized to be involved in multiple biological processes, and to affect proteins physical properties, and has consequentially been labeled a critical quality attribute of biopharmaceuticals. Additionally, due to recent advances in analytical methods and analysis software, glycosylation is targeted in the search for disease biomarkers for early diagnosis and patient stratification. Biofluids such as saliva, serum or plasma are of great use in this regard, as they are easily accessible and can provide relevant glycosylation information. Thus, as the assessment of protein glycosylation is becoming a major element in clinical and biopharmaceutical research, this review aims to convey the current state of knowledge on the N-glycosylation of the major plasma glycoproteins alpha-1-acid glycoprotein, alpha-1-antitrypsin, alpha-1B-glycoprotein, alpha-2-HS-glycoprotein, alpha-2-macroglobulin, antithrombin-III, apolipoprotein B-100, apolipoprotein D, apolipoprotein F, beta-2-glycoprotein 1, ceruloplasmin, fibrinogen, immunoglobulin (Ig) A, IgG, IgM, haptoglobin, hemopexin, histidine-rich glycoprotein, kininogen-1, serotransferrin, vitronectin, and zinc-alpha-2-glycoprotein. In addition, the less abundant immunoglobulins D and E are included because of their major relevance in immunology and biopharmaceutical research. Where available, the glycosylation is described in a site-specific manner. In the discussion, we put the glycosylation of individual proteins into perspective and speculate how the individual proteins may contribute to a total plasma N-glycosylation profile determined at the released glycan level.

Rotational thromboelastometry–guided blood product management in major spine surgery

OBJECT

Major spinal surgery in adult patients is often associated with significant intraoperative blood loss. Rotational thromboelastometry (ROTEM) is a functional viscoelastometric method for real-time hemostasis testing. In this study, the authors sought to characterize the coagulation abnormalities encountered in spine surgery and determine whether a ROTEM-guided, protocol-based approach to transfusion reduced blood loss and blood product use and cost.

METHODS

A hospital database was used to identify patients who had undergone adult deformity correction spine surgery with ROTEM-guided therapy. All patients who received ROTEM-guided therapy (ROTEM group) were matched with historical cohorts whose coagulation status had not been evaluated with ROTEM but who were treated using a conventional clinical and point-of-care laboratory approach to transfusion (Conventional group). Both groups were subdivided into 2 groups based on whether they had received intraoperative tranexamic acid (TXA), the only coagulation-modifying medication administered intraoperatively during the study period. In the ROTEM group, 26 patients received TXA (ROTEM-TXA group) and 24 did not (ROTEM-nonTXA group). Demographic, surgical, laboratory, and perioperative transfusion data were recorded. Data were analyzed by rank permutation test, adapted for the 1:2 ROTEM-to-Conventional matching structure, with p < 0.05 considered significant.

RESULTS

Comparison of the 2 groups in which TXA was used showed significantly less fresh-frozen plasma (FFP) use in the ROTEM-TXA group than in the Conventional-TXA group (median 0 units [range 0–4 units] vs 2.5 units [range 0–13 units], p < 0.0002) but significantly more cryoprecipitate use (median 1 unit [range 0–4 units] in the ROTEM-TXA group vs 0 units [range 0–2 units] in the Conventional-TXA group, p < 0.05), with a nonsignificant reduction in blood loss (median 2.6 L [range 0.9–5.4 L] in the ROTEM-TXA group vs 2.9 L [0.7–7.0 L] in the Conventional-TXA group, p = 0.21). In the 2 groups in which TXA was not used, the ROTEM-nonTXA group showed significantly less blood loss than the Conventional-nonTXA group (median 1 L [range 0.2–6.0 L] vs 1.5 L [range 1.0–4.5 L], p = 0.0005), with a trend toward less transfusion of packed red blood cells (pRBC) (median 0 units [range 0–4 units] vs 1 unit [range 0–9 units], p = 0.09]. Cryoprecipitate use was increased and FFP use decreased in response to ROTEM analysis identifying hypofibrinogenemia as a major contributor to ongoing coagulopathy.

CONCLUSIONS

In major spine surgery, ROTEM-guided transfusion allows for standardization of transfusion practices and early identification and treatment of hypofibrinogenemia. Hypofibrinogenemia is an important cause of the coagulopathy encountered during these procedures and aggressive management of this complication is associated with less intraoperative blood loss, reduced transfusion requirements, and decreased transfusion-related cost.

Getting there--working toward minimizing blood loss in scoliosis surgery

Ryan KM, O'Brien K, Reqan I, O'Byrne JM, Moore D, Kelly PM, et al. The prevalence of abnormal preoperative coagulation tests in pediatric patients undergoing spinal surgery for scoliosis. Spine J 2015;15:1217-22 (in this issue).

The prevalence of abnormal preoperative coagulation tests in pediatric patients undergoing spinal surgery for scoliosis

BACKGROUND CONTEXT

Multilevel spinal fusion surgery for deformity correcting spinal surgery in pediatric patients with scoliosis has typically been associated with significant blood loss. The mechanism of bleeding in such patients is not fully understood. Coagulation abnormalities, which may be associated with scoliosis, are thought to play a role.

PURPOSE

To document and compare the prevalence of preoperative coagulation abnormalities among patients with scoliosis attending a pediatric orthopedic department for spinal fusion surgery with patients attending for minor surgery.

STUDY DESIGN

An observational study. All patients were recruited from a pediatric tertiary referral center in Dublin, Ireland.

PATIENT SAMPLE

Coagulation profile results were prospectively collected over a 2-year period from 165 spinal surgery patients. In total, 175 patients were included in the non-scoliosis group. These patients attended the day ward for minor procedures and were recruited over a 4-month period.

OUTCOME MEASURES

The primary outcome measure was the coagulation profiles, which included prothrombin time, activated partial thromboplastin time (APTT), and thrombin time (TT). Levels of Coagulation Factors II, V, VII, and X were also recorded.

METHODS

All blood samples were sent to the haematology laboratory to establish the coagulation profile. The primary outcome was the presence of an abnormal coagulation screening test (if any of PT, APTT, or TT were abnormal). Prothrombin time, APTT, and TT were also analyzed as individual continuous variables, as well as Coagulation Factors II, V, VII, and X. Regression analysis was used to compare the coagulation profile of scoliosis patients with that of non-scoliosis patients. There were no outside funding sources or any potential conflict of interest associated with this study.

RESULTS

The scoliosis patients were more likely to have an abnormal preoperative screening test compared with non-scoliosis patients, with an odds ratio of 2.6. Further analysis showed statistically significant longer clotting times for patients with scoliosis compared with those without; PT (t=3.37, p=.001), APTT (t=4.26, p<.001), TT (t=4.52, p<.001). Of the coagulation factors analyzed, only factor X was significantly different in scoliosis patients compared with non-scoliosis controls (t=-4.41, p<.001).

CONCLUSIONS

Children with scoliosis have a higher prevalence of preoperative coagulation abnormalities compared with normal healthy patients.

Higher fibrinogen concentrations for reduction of transfusion requirements during major paediatric surgery: A prospective randomised controlled trial

BACKGROUND

Hypofibrinogenaemia is one of the main reasons for development of perioperative coagulopathy during major paediatric surgery. The aim of this study was to assess whether prophylactic maintenance of higher fibrinogen concentrations through administration of fibrinogen concentrate would decrease the volume of transfused red blood cell (RBCs).

METHODS

In this prospective, randomised, clinical trial, patients aged 6 months to 17 yr undergoing craniosynostosis and scoliosis surgery received fibrinogen concentrate (30 mg kg(-1)) at two predefined intraoperative fibrinogen concentrations [ROTEM(®) FIBTEM maximum clot firmness (MCF) of <8 mm (conventional) or <13 mm (early substitution)]. Total volume of transfused RBCs was recorded over 24 h after start of surgery.

RESULTS

Thirty children who underwent craniosynostosis surgery and 19 children who underwent scoliosis surgery were treated per protocol. During craniosynostosis surgery, children in the early substitution group received significantly less RBCs (median, 28 ml kg(-1); IQR, 21 to 50 ml kg(-1)) compared with the conventional fibrinogen trigger of <8 mm (median, 56 ml kg(-1); IQR, 28 to 62 ml kg(-1)) (P=0.03). Calculated blood loss as per cent of estimated total blood volume decreased from a median of 160% (IQR, 110-190%) to a median of 90% (IQR, 78-110%) (P=0.017). No significant changes were observed in the scoliosis surgery population. No bleeding events requiring surgical intervention, postoperative transfusions of RBCs, or treatment-related adverse events were observed.

CONCLUSIONS

Intraoperative administration of fibrinogen concentrate using a FIBTEM MCF trigger level of <13 mm can be successfully used to significantly decrease bleeding, and transfusion requirements in the setting of craniosynostosis surgery, but not scoliosis.

CLINICAL TRIAL REGISTRY NUMBER

ClinicalTrials.gov NCT01487837.

Preoperative hypofibrinogenemia is associated with increased intraoperative bleeding in ruptured abdominal aortic aneurysms

INTRODUCTION

Ruptured abdominal aortic aneurysm (rAAA) is associated with coagulopathy and intraabdominal hemorrhage. Fibrinogen acts as a key coagulation factor and has previously been suggested as a biomarker for increased perioperative bleeding in other surgical areas. The aim of the present study was to investigate fibrinogen and standard laboratory parameters and their association to preoperative hemodynamic status, intraoperative bleeding (IOB), and outcome in treatment of rAAA.

METHODS

This is a single university center retrospective cohort study of 91 consecutive patients with rAAA undergoing open surgery or endovascular aneurysm repair (EVAR) between 2008 and 2013. Patients were analyzed using the Swedish Vascular Registry (Swedvasc), and local hospital medical and laboratory records. Laboratory data analyzed included fibrinogen, hemoglobin, platelet count, prothrombin time ratio, activated partial thrombin time, and creatinine. Odds ratios (OR) with 95% confidence intervals (CI) were calculated in a logistical regression model.

RESULTS

In the study cohort (n = 91), median age was 74 (57-91) years; 80 % men; open surgical repair (n = 72; 77%); EVAR (n = 19; 23%). Median preoperative fibrinogen concentration was 1.8 g/L (IQR = 1.4) and varied significantly across bleeding groups: ≤1999 ml 2.3g/L, IQR = 1.4 (n = 35); 2000-4999 ml 1.6 g/L, IQR = 1.5 (n = 33); ≥5000 ml 1.4 g/L, IQR = 1.0 (n = 23) (P < 0.001). Preoperative fibrinogen concentration showed a linear relationship with preoperative blood pressure (r = .447, P = 0.01). When analyzing other preoperative laboratory values, only platelets showed a similar linear relationship with preoperative blood pressure (r = .247, P = 0.05). Patients with blood pressure <70 mmHg had an associated median fibrinogen concentration of less than 1.5 g/L (P = 0.001). In the multivariable logistic regression analysis, preoperative fibrinogen < 1.5 g/L [OR 10.0, CI (1.8-57.1), P = 0.009] was associated with IOB >2000 ml and preoperative blood pressure < 70 mmHg was associated with IOB >2 000 ml [OR 3.7, CI (1.1-12.6), P = 0.03] and >5000 ml [OR 5.2, CI (1.3-21.1), P = 0.02]. Low fibrinogen concentration (< 1.5 g/L) was associated with 30-day mortality in the univariate analysis but not in the multivariable logistic regression analysis.

CONCLUSION

Low preoperative fibrinogen concentration was significantly associated with preoperative hypotension and increased intraoperative bleeding in patients with rAAA. Patients in hemodynamic shock with blood pressure <70 mmHg had an associated fibrinogen concentration of less than 1.5 g/L. A fibrinogen concentration less than 1.5 g/L was associated with a ten-fold increased risk of intraoperative hemorrhage of more than 2000 ml.

Blood loss during posterior spinal fusion for adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective uncontrolled case series.

OBJECTIVE

The purpose of this study was to determine the association, if any, between intraoperative blood loss and need for transfusion with the use of periapical (Ponte) osteotomies, as well as other patient and surgical variables among patients with adolescent idiopathic scoliosis (AIS) undergoing posterior spinal instrumentation and fusion.

SUMMARY OF BACKGROUND DATA

Blood loss during posterior spinal fusion for AIS can be substantial. Numerous techniques are used to minimize intraoperative blood loss and the need for allogeneic transfusion. However, it is unclear which patient and surgeon variables affect blood loss most significantly.

METHODS

A review was conducted on consecutive patients with AIS who had undergone posterior spinal fusion from July 1997 to February 2013 by a single primary surgeon at 1 institution. The relationship of estimated blood loss, normalized blood loss (normalized blood loss = estimated blood loss/number of levels fused/patient's weight in kilograms), autologous blood retrieved, and allogeneic transfusion received with various patient- and procedure-related variables were analyzed.

RESULTS

Estimated blood loss, normalized blood loss, and autologous blood retrieved were higher in patients who underwent periapical Ponte osteotomies (n = 38) (P < 0.0001, P < 0.001, P < 0.01, respectively). The mean major curve correction was 64% in patients without osteotomies, and 65% in patients with osteotomies (P = 0.81). All patients who underwent osteotomies (38/38) received allogeneic transfusion versus 26% (19/73) of those without osteotomies (P < 0.001). The likelihood of transfusion correlated with increasing number of osteotomies and a lower preoperative hemoglobin level (odds ratio, 3.34; P = 0.003; and odds ratio, 0.51; P = 0.02, respectively).

CONCLUSION

In patients with AIS undergoing posterior spinal fusion with instrumentation, performing periapical osteotomies increased all measures of intraoperative blood loss and need for transfusion without substantially improving major curve correction. As expected, a lower preoperative hemoglobin level was observed in patients who received a blood transfusion after posterior instrumentation and fusion.

LEVEL OF EVIDENCE

4.

Predicting excessive hemorrhage in adolescent idiopathic scoliosis patients undergoing posterior spinal instrumentation and fusion

BACKGROUND CONTEXT

Blood loss in patients with adolescent idiopathic scoliosis (AIS) who are undergoing posterior spinal instrumentation and fusion (PSIF) varies greatly. The reason for this wide range is not clear. There are reports of unexpected massive hemorrhage during these surgeries. Many studies reflect authors' preferences for describing blood loss in terms of levels fused, weight, or percent blood volume.

PURPOSE

We sought to define excessive blood loss clinically, determine its incidence in our study population, and identify associated variables. Results are intended to inform perioperative preparation for these cases. Results may be used to inform prospective study designs.

STUDY DESIGN

This was a retrospective uncontrolled case series.

PATIENT SAMPLE

A total of 311 consecutive AIS PSIF cases during the years 2005-2010 performed at Children's Hospital Colorado were studied.

OUTCOME MEASURES

We measured estimated blood loss (EBL) and its association with multiple patient, surgical, and anesthetic variables.

METHODS

Thirty-one variables potentially related to blood loss were collected retrospectively from electronic medical records for analysis. When no cases of clearly excessive blood loss were identified on the basis of visual examination of EBL distribution, we chose to use the top 10% of blood loss cases as an arbitrary determinant of excessive blood loss. Three cut-off strategies captured the top 10% of EBL cases with little variation in who was selected: 1) >1,700 mL of EBL, 2) >50% EBL/estimated blood volume, and 3) >150 mL/level fused EBL. Variables were compared with the χ(2) test, Fisher exact, or t-tests, when appropriate. A generalized linear mixed logistic model was used to determine the probability of excessive blood loss based on the number of levels fused.

RESULTS

The average EBL was 89.17 mL/level fused (range, 45-133 mL). EBL fit a progressively wider distribution as surgical complexity (number of levels fused) increased. Number of levels fused (p<.0001), operative time (p=.0139), number of screws (p<.0001), and maximal preoperative Cobb angle (p=.0491) were significantly associated with excessive blood loss. The variable that was most strongly associated with excessive blood loss was the number of levels fused, with ≥12 levels having a probability of >10% of excessive hemorrhage.

CONCLUSION

Excessive blood loss may be an arbitrary number until future research suggests otherwise. We show that the probability of exceeding one of our arbitrary definitions is approximately 10% when 12 or more levels are fused. If a 10% incidence of excessive blood loss is determined to be clinically relevant, teams might wish to pursue hematologic consultation and maximal blood conservation strategy when 12 or more levels are planned for fusion.

Fibrinogen but not factor XIII deficiency is associated with bleeding after craniotomy

BACKGROUND

Postoperative haemorrhage in neurosurgery is associated with significant morbidity and mortality. There is controversy whether or not factor XIII (FXIII) deficiency leads to bleeding complications after craniotomy. Decreased fibrinogen levels have been associated with an increased incidence of bleeding complications in cardiac and orthopaedic surgery. The aim of this study was to assess perioperative fibrinogen and FXIII levels in patients undergoing elective intracranial surgery with and without severe bleeding events.

METHODS

Perioperative FXIII and fibrinogen levels were prospectively assessed in 290 patients undergoing elective craniotomy. Patients were divided into two groups according to the presence or absence of severe bleeding requiring surgical revision. Coagulation test results of these groups were compared using Student's t-test.

RESULTS

The incidence of postoperative severe bleeding was 2.4%. No differences in FXIII levels were observed, but postoperative fibrinogen levels were significantly lower in patients suffering from postoperative haematoma compared with those without postoperative intracranial bleeding complications [237 mg dl(-1) (standard deviation, SD 86) vs 170 mg dl(-1) (SD 35), P=0.03]. The odds ratio for postoperative haematoma in patients with a postoperative fibrinogen level below 200 mg dl(-1) was 10.02 (confidence interval: 1.19-84.40, P=0.03).

CONCLUSIONS

This study emphasizes the role of fibrinogen as potentially modifiable risk factor for perioperative bleeding in intracranial surgery. Future randomized controlled trials will be essential to identify patients who might benefit from fibrinogen substitution during neurosurgical procedures.

Management of hemorrhage in cardiothoracic surgery

Bleeding is an important issue in cardiothoracic surgery, and about 20% of all blood products are transfused in this clinical setting worldwide. Transfusion practices, however, are highly variable among different hospitals and more than 25% of allogeneic blood transfusions have been considered inappropriate. Furthermore, both bleeding and allogeneic blood transfusion are associated with increased morbidity, mortality, and hospital costs. In the past decades, several attempts have been made to find a universal hemostatic agent to ensure hemostasis during and after cardiothoracic surgery. Most drugs studied in this context have either failed to reduce bleeding and transfusion requirements or were associated with severe adverse events, such as acute renal failure or thrombotic/thromboembolic events and, in some cases, increased mortality. Therefore, an individualized goal-directed hemostatic therapy ("theranostic" approach) seems to be more appropriate to stop bleeding in this complex clinical setting. The use of point-of-care (POC) transfusion and coagulation management algorithms guided by viscoelastic tests such as thromboelastometry/thromboelastography in combination with POC platelet function tests such as whole blood impedance aggregometry, and based on first-line therapy with fibrinogen and prothrombin complex concentrate have been associated with reduced allogeneic blood transfusion requirements, reduced incidence of thrombotic/thromboembolic and transfusion-related adverse events, and improved outcomes in cardiac surgery. This article reviews the current literature dealing with the management of hemorrhage in cardiothoracic surgery based on POC diagnostics and with specific coagulation factor concentrates and its impact on transfusion requirements and patients' outcomes.

Severe bleeding in surgical and trauma patients: the role of fibrinogen replacement therapy

Fibrinogen is in a central position in the coagulation system, playing an important role in platelet aggregation and establishing the fibrin network. Fibrinogen is also the first coagulation factor to become critically low during surgery and after major trauma. Hemostatic support has traditionally involved using transfusion of allogeneic blood products, including fresh frozen plasma; however, there is a lack of conclusive evidence supporting the clinical effectiveness of fresh frozen plasma in these situations. Early, targeted fibrinogen substitution may be preferable in terms of speed of administration and clinical effectiveness, with recent studies adding to the weight of evidence demonstrating the potential to significantly reduce blood loss and transfusion requirements in surgical and severe trauma patients with this approach. The availability of point-of-care testing using viscoelastic techniques to guide fibrinogen substitution has enabled the development of transfusion algorithms that lead to individualized, goal-directed, and targeted use of fibrinogen concentrates to improve clinical outcomes. Fibrinogen replacement has become the standard-of-care in several major surgical centers in Europe and is recommended in current European trauma treatment guidelines. Future prospective studies will help to establish the critical threshold and target levels for fibrinogen substitution in different acute-care situations and should encourage more widespread use of this rational and effective approach to the treatment of bleeding-induced coagulopathies.

Thromboelastometry guided therapy of severe bleeding. Essener Runde algorithm

Both, severe haemorrhage and blood transfusion are associated with increased morbidity and mortality. Therefore, it is of particular importance to stop perioperative bleeding as fast and as possible to avoid unnecessary transfusion. Viscoelastic test (ROTEM® or TEG®) allow for early prediction of massive transfusion and goal-directed therapy with specific haemostatic drugs, coagulation factor concentrates, and blood products. Growing consensus points out, that plasma-based coagulation screening tests like aPTT and PT are inappropriate for monitoring coagulopathy or guide transfusion therapy. Increasing evidence of more than 5000 surgical or trauma patients points towards the beneficial effects of a thrombelastography or -metry based approach in diagnosis and goal-directed therapy of perioperative massive haemorrhage. The Essener Runde task force is a group of clinicians of various specialties (anaesthesiology, intensive care, haemostaseology, haematology, internal medicine, transfusion medicine, surgery) interested in perioperative coagulation management. The ROTEM diagnostic algorithm of the Essener Runde task force was created to standardise and simplify the interpretation of ROTEM® results in perioperative settings and to present their possible implications for therapeutic interventions in severe bleeding. To exemplify, this text mainly focuses on coagulation management in trauma.

Fast interpretation of thromboelastometry in non-cardiac surgery: reliability in patients with hypo-, normo-, and hypercoagulability

BACKGROUND

Conventional coagulation test are not useful to guide haemostatic therapy in severe bleeding due to their long turn-around time. In contrast, early variables assessed by point-of-care thromboelastometry (ROTEM(®)) are available within 10-20 min and increasingly used to guide haemostatic therapy in liver transplantation and severe trauma. However, the reliability of early ROTEM(®) variables to predict maximum clot firmness (MCF) in non-cardiac surgery patients with subnormal, normal, and supranormal MCF has not yet been evaluated.

METHODS

Retrospective data of 14,162 ROTEM(®) assays (3939 EXTEM(®), 3654 INTEM(®), 3287 FIBTEM(®), and 3282 APTEM(®) assays) of patients undergoing non-cardiac surgery were analysed. ROTEM(®) variables [clotting time (CT), clot formation time (CFT), α-angle, A5, A10, and A15] were related to MCF by linear or non-linear regression, as appropriate. The Bland-Altman analyses to assess the bias between early ROTEM(®) variables and MCF and receiver operating characteristics (ROC) were also performed.

RESULTS

Taking the best and worst correlation coefficients for each assay type, CT (r=0.18-0.49) showed the worst correlation to MCF. In contrast, α-angle (r=0.85-0.88) and CFT (r=0.89-0.92) demonstrated good but non-linear correlation with MCF. The best and linear correlations were found for A5 (r=0.93-0.95), A10 (r=0.96), and A15 (r=0.97-0.98). ROC analyses provided excellent area under the curve (AUC) values for A5, A10, and A15 (AUC=0.962-0.985).

CONCLUSIONS

Early values of clot firmness allow for fast and reliable prediction of ROTEM(®) MCF in non-cardiac patients with subnormal, normal, and supranormal MCF values and therefore can be used to guide haemostatic therapy in severe bleeding.

Risk factors and outcomes of massive red blood cell transfusion following living donor liver transplantation

OBJECTIVES

To identify the factors influencing blood loss and secondary blood transfusion and to investigate the outcomes of patients who underwent a massive blood transfusion (MBT) following living donor liver transplantation (LDLT).

METHODS

Patients who underwent primary adult-to-adult right hepatic lobe LDLT were included in the study, and were divided into the MBT group [≥6 red blood cell (RBC) units in 24 h] and the non-massive blood transfusion (NMBT) group (<6 RBC units in 24 h). All potential risk factors, length of intensive care unit (ICU) stay and long-term survival rate of the patients in the two groups were analyzed.

RESULTS

The data of 181 eligible patients were retrospectively analyzed. A decreased long-term survival rate, a higher incidence of postoperative infection and prolonged ICU stay were observed in the MBT group. No significant difference was observed in survival rate between patients having platelet transfusion>2 units and ≤2 units. Hemoglobin<100 g/L, platelet counts<70×10(9)/L, fibrinogen level<1.5 g/L and history of upper abdominal surgery were found to be independent risk factors.

CONCLUSIONS

Blood transfusion during LDLT can be predicted using preoperative variables. Massive RBC transfusion may lead to poor long-term survival, higher postoperative infection rate and prolonged ICU stay. Platelet transfusion may not be a risk factor for long-term survival.